Foundations Of Cognitive Science

Cognitive Penetrability

Cognitive penetrability is an approach to testing strong equivalence. It does so by investigating whether a function of interest is primitive or not (i.e. is part of the functional architecture or not). If the systematic manipulation of beliefs or cognitive contents affects the performance of the function in a rational way (i.e. the function changes in a way that "makes sense" given the content manipulation) then the function is said to be cognitively penetrable, and is therefore not part of the architecture (Pylyshyn, 1984). If such belief changes do not affect the function, then it is said that the function is cognitively impenetrable, which supports claims that it is part of the functional architecture.

The cognitive penetrability approach was used in the imagary debate in cognitive science in the 1980's. (Pylyshyn, 1984). It has also been applied to the study of the nature of processing of apparent motion ()


  1. Pylyshyn, Z. W. (1984). Computation And Cognition. Cambridge, MA.: MIT Press.
  2. Wright, R. D., & Dawson, M. R. W. (1994). To what extent do beliefs affect apparent motion? Philosophical Psychology, 7, 471- 491.

(Revised December 2009)